ACT Policing recorded 224 reported rapes in the two years to May 2017, but made just 65 rape charges, documents obtained under freedom of information laws revealed.

Separate court figures for roughly the same period showed only a small proportion of sexual offences brough to court led to a conviction.

From July 1, 2015 to May 19 this year, 78 of the 159 sexual offences that went to the magistrate and children cases went to the supreme court. Of those, 54 were proved guilty. This data was provided by the Commonwealth Director of Public Prosecutions ACT.

ACT Victims of Crime Commissioner John Hinchey said the statistics reflected the challenges police face in proving sexual assault beyond reasonable doubt.

"Police do a very good job in responding to sexual assaults," he said.

"They manage people very well in those circumstances, but it is a high threshold of proof that is required and that can be very frustrating for police to manage."

After police take an initial report from sexual assault victims, specialist officers gather a full version of events.

But Mr Hinchey highlighted how the majority of victims never contact police. According to the Australian Bureau of Statistics, roughly one in five female victims of sexual assault in Australia report the crime.

"I think that immediately following a sexual assault, victims are so often traumatised that the best they can do is to survive and to manage their trauma, and that the thought of going to a public authority about that is just too difficult for many," Mr Hinchey said.

"They are asked to disclose information about themselves after which they have very little control about how that information will be used or made public. Too often our community puts an element of blame to victims of these offences and it's that stigmatisation that drives these offences away from our criminal justice system."

For some sexual offence victims, including children, the police will record the interview to be used in court as evidence. It can be challenging for police to decide whether there is enough evidence to prosecute, for which they can consult with the office of the Director of Public Prosecutions.

The Director of Public Prosecutions Jon White said the decision to proceed with a prosecution is based on a two-stage test.

"Is there a reasonable prospect of conviction, which requires an evaluation of the available evidence, and if there is, whether it is in the interest of the public for the matter to proceed," Mr White said.

"There are many factors to be taken into account, but it must always be remembered that the criminal law reflects the community's pursuit of justice, which in alleged crimes of this type is particularly engaged."

Mr White said most sexual assault chargers end in a court verdict.

But as the statistics show, sexual assault offences are notoriously difficult to prove in court.

Mr Hinchey said the low conviction rate compared to the scale of sexual assaults is another dissuading factor for many victims.

"Our justice process is less-than-perfect to a victim of sexual assault in particular, and the process itself can be so daunting and threatening to their wellbeing that victims often decide not to report sexual offences," he said.

A Victorian government survey released in 2014 on national community attitudes of violence towards women found a high proportion of Australians endorse attitudes that minimise and trivialise rape.

Mr Hinchey stressed the need for reduced stigma about rape and violence.

"The more that we talk about sexual assault as a community and face the challenges that we have in bringing the offenders to justice, the more confidence people will have to speak out," he said.

"The more stories people tell about their experiences, the stronger position we will be in to respond appropriately."